Pneumatic insect robots

ABSTRACT

A modular pneumatic robotic actuator, including a first elongated hollow structure and a second elongated hollow structure connected to each other at a moveable joint; an inflatable bladder comprised of an elastomeric material disposed at the said joint and immobilized between the first and second hollow structures, wherein the said inflatable bladder inflates preferentially away from the joint; and a restraining membrane comprised of an elastomeric material disposed over the bladder and connecting the first and second hollow structures, wherein the said restraining membrane is relaxed when the bladder is deflated.

CROSS REFERENCE TO RELATED APPLICATION

The present application is a continuation of U.S. patent applicationSer. No. 14/752,558, entitled “Pneumatic Insect Robots,” filed on Jun.26, 2015, which claims the benefit of priority from U.S. PatentApplication No. 62/017,606, filed on Jun. 26, 2014, the disclosures ofeach of which are incorporated herein in their entirety by referencethereto.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

The present invention was made with United States government supportunder Grant No. W911NF-11-1-0094 awarded by the Defense AdvancedResearch Planning Agency. The United States government has certainrights in this invention.

BACKGROUND

Robots, like animals, are typically designed for five fundamentalfunctions, namely, sensing, signaling, motion, intelligence and a sourceof energy. Industrial robots, that perform repetitive or explicitlydefined functions in a static, mapped environment (e.g., robot arms)require: sensors to determine their position; lights to signal activity;electronic motors to move their limbs or grippers; a computer to directthe motion and run feedback loops and a tethered, electrical supply ofpower.

In contrast, service robots must be capable of interacting safely withhumans in a dynamic, unmapped environment. These types of robotstypically require sensors that are capable of detecting obstacles; acomputer running sophisticated software to direct their motion andenvironmental interactions and a source for power. Nevertheless, theserobots also suffer from drawbacks. The requirements of being able todynamically sense, learn, and interact safely with an unmappedenvironment causes these robots to be slow and the power requirementsfor computers, motors and batteries results in excessive cost forfabrication of these robots.

Robotic systems used for industrial automation or service robots aremanufactured from precisely machined hard parts with electric motorsthat require sensors to enable accurate control of their motion.Suitable examples of these sensors are cameras, accelerometers, andposition encoders that provide the input to feedback loops. Thealgorithms used in this type of active control systems work well instatic, well defined, and pre-mapped environments, but often have greatdifficulty adapting to the kinds of unstructured and complex terrainsfound in nature.

In contrast, insects such as spiders and cockroaches possess compliantstructures or limbs that enable passive adaptability to unpredictableand dynamic environments, without requiring a complex control system.The control system in these animals is referred to as “embodiedintelligence” and extends beyond the brain and into the physical designand construction of the body and limbs of the insect, which is analogousto the electronic system and actuators of the robot, respectively.

The design principle of “embodied intelligence,” places some control andmechanical compliance directly into the limbs of the robots. Using thisprinciple a new trend has emerged in the robotics industry and are seenin robots such as RHex (Kod Lab, UPenn), or DASH (BiomimeticMillisystems Lab, Berkley). Newer industrial robots such as Baxter(Rethink Robotics) rely on Series Elastic Actuators that couple electricmotors to the limbs using an elastic linkage. This design provides therobotic arms with lower reflected mechanical impedance and increasessafety in the human-robot interaction.

In an attempt to mimic the functions of gripping, camouflage, andlocomotion found in animals such as the octopus or squid, softelastomers have recently been used to develop a new type ofnature-inspired robot, called “soft robots.” These “soft robots” aretypically designed using silicone elastomers that are less dense andmore flexible than the metals used in conventional “hard robots.” Due totheir inherent mechanical compliance and the fact that they are softerthan humans, these robots are capable of interacting safely in adynamic, unmapped environment without inflicting any harm. However, asize limitation is imposed due to the low stiffness-to-density-ratio(κ:ρ) of the material. Silicone elastomers are too heavy to be used assupport material in medium to large-scale robots that need to movequickly and efficiently.

In nature, the above problem is addressed by combining materials withcomplementary properties. A low-density material such as bone is used toform the load bearing skeletal support, whereas a higher-densitymaterial like muscle is used to actuate motion. This facilitates supportof a larger amount of weight while at the same time allowing for quickand efficient operation with a greater range of motion. Further, natureuses tendons in the joints to store energy in the extension phase of thegait which is released on contraction. This increase the animal's outputpower and mechanical efficiency.

In an effort to recreate this power and efficiency, new robotic jointsthat are modular in nature and combine an elastomeric actuation devicewith a structural support are desired. Currently, robots of this sortthat are light-weight, low-cost, and do not require elaborate assemblyand fabrication are not available.

SUMMARY

This disclosure describes modular pneumatic robotic actuators that canfunction as robotic joints. The actuators include soft elastomericbladder immobilized by hollow tubular structures that are bent in theirresting state. Upon actuation of the robotic joint, the elastomericbladder expands, causing movement of the hollow tubular structure aroundthe joint the place where the defect was introduced.

A method of fabrication of the pneumatic robotic actuator and furtherthe fabrication of pneumatic insect-inspired robots is described.

In one aspect, a modular pneumatic robotic actuator includes a firstelongated hollow structure and a second elongated hollow structureconnected to each other in a way that creates a moveable joint about thepoint of contact. Inside, there is an inflatable bladder made of anelastomeric material is disposed at the joint and immobilized betweenthe first or second hollow structure, wherein the inflatable bladderinflates preferentially away from the joint; and a restraining membranemade of an elastomeric material is disposed over the bladder andconnects the first and second hollow structures. The restrainingmembrane is in a relaxed position when the bladder is deflated.

In one or more embodiments, the first and second hollow structuresprovide a first preselected angle at the joint when the restrainingmembrane is in a relaxed position.

In any of the preceding embodiments, the first and second hollowstructures provide a second preselected angle at the joint when therestraining membrane is in an actuated position.

In any of the preceding embodiments, the inflatable bladder can bepressurized to inflate from a relaxed position to an actuated position,wherein the bladder is positioned to exert a positive pressure on therestraining membrane.

In any of the preceding embodiments, the restraining membrane brings thefirst and second hollow structures from the actuated position to therelaxed position upon removal of pressure in the inflatable bladder.

In any of the preceding embodiments, the first and second elongatedhollow structure is made of a low density material capable of holdingthe structure of the robot.

In any of the preceding embodiments, the first and second elongatedhollow structure is made of a low density material, wherein the materialis selected from a group consisting of aluminum, copper, brass,polypropylene, poly(vinyl chloride), polycarbonate,poly(tetrafluoroethylene), polyisobutylene, polystyrene,polyacrylonitrile, poly(methyl acrylate), poly(methyl methacrylate),polybutadiene, polychloroprene, poly(cis-1,4-isoprene), andpoly(trans-1,4-isoprene).

In any of the preceding embodiments, the inflatable elastic bladder andthe restraining membrane are made of an elastomeric material selectedfrom the group consisting of polyisoprene, polybutadiene, polyurethane,polychloroprene, butyl rubber, halogenated butyl rubber,styrene-butadiene rubber, nitrile rubber, hydrogenated nitrile rubber,ethylene propylene rubber, ethylene propylene diene rubber,epichlorohydrin rubber, polyacrylic rubber, silicone rubber,fluorosilicone rubber, fluoroelastomers, perfluoroelastomers, polyetherblock amides, chlorosulfonated polyethylene, ethylene-vinyl acetate, andpolysulfide rubber.

In any of the preceding embodiments, the inflatable bladder, therestraining membrane and a substantial part of the first and secondhollow structures of the pneumatic actuator joint are covered by afabric material. In some of the embodiments, the fabric materialprovides additional reinforcement to the pneumatic actuator joint. Asuitable example of fabric material that can be used for this purpose isspandex.

In any of the preceding embodiments, the joint is a thinned strip of thesame material used for the first and second hollow elements. In someembodiments, the joint is integral with the first and second hollowelements.

In any of the preceding embodiments, the joint is a thinned strip madeof a different material other than the first and second hollow elements.

In some embodiments, the thinned strips are glued to the end of thefirst and second hollow element where they are connected.

In some embodiments, the joint is a pin.

In some embodiments, the joint is a ring that passes through a holelocated at the end of the first and second hollow element where the twohollow elements are connected

In some embodiments, the joint is a hinge. In some embodiments, the endsof the hinge are glued or screwed on to the end of the first and secondhollow element where they are connected.

In another aspect, a method of actuating the modular pneumatic actuatorin any of the preceding embodiments in an actuated position is performedby pressurizing the inflatable bladder with a gas, wherein the bladdermaterial expands to exert a positive pressure on the restrainingmembrane and a force on the first and second hollow structures, whereinthe said positive pressure causes the restraining structure to bestrained in a direction away from the joint of the first and secondhollow structure and creates a force that causes the ends of the hollowstructures to move apart about the joint.

In another aspect, a method of actuating the modular pneumatic actuatorin any of the preceding embodiments into a relaxed position includesdepressurizing the inflatable bladder filled with a gas to deflate it,wherein deflating the bladder causes the restraining membrane to exert apositive pressure on the bladder material and a force on the first andsecond hollow structures in the inward direction towards the joint,wherein the said force on the first and second hollow structures causesthe distal end of the first and the second hollow structures to movetowards each other about the joint.

In another aspect, a modular pneumatic robot limb includes, at least twomodular pneumatic robotic actuators according to any of the precedingembodiments.

In another aspect, a modular pneumatic robot limb includes, two modularpneumatic robotic actuators according to any of the precedingembodiments.

In another aspect, a modular pneumatic robot limb includes, four modularpneumatic robotic actuators according to any of the precedingembodiments.

In any of the preceding embodiments, the modular pneumatic roboticactuators can be individually actuated or relaxed.

In another aspect, a modular pneumatic robot includes, at least onemodular pneumatic robot limb according to any of the precedingembodiments.

In another aspect, a modular pneumatic robot comprising, one modularpneumatic robot limb according to any of the preceding embodiments.

In another aspect, a modular pneumatic robot comprising, two modularpneumatic robot limbs according to any of the preceding embodiments.

In another aspect, an insect robot comprising, four modular pneumaticrobotic actuators according to any of the preceding embodiments.

In another aspect, a method of moving the modular pneumatic robotsaccording to any of the preceding embodiments includes actuating andrelaxing the modular pneumatic actuator according to any of thepreceding embodiments in a predetermined sequence.

In another aspect, a method according to any of the precedingembodiments, wherein the predetermined sequence includes bringing one ofthe two adjacent actuators into actuated position while the otherremains in relaxed position.

In another aspect, a method according to any of the precedingembodiments, wherein the predetermined sequence comprises of bringingtwo adjacent actuators into actuated position.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1A is a schematic of an embodiment of the assembled pneumaticactuator joint when the actuator is in unpressurized position

FIG. 1B is a schematic that shows that varying the angle of cut of firstand second hollow structures with respect to the central axis of firstand second hollow structures governs the angle that is achieved in therelaxed position.

FIG. 2 is a schematic illustration of an embodiment of an assembledpneumatic actuator joint when the actuator is in actuated position.

FIG. 3 shows the various components used for making the modularpneumatic actuator joint according to one embodiment

FIG. 4 is a photograph of a pneumatic actuator joint prepared using thematerials and components shown in FIG. 3 in relaxed position where theangle between the first and second hollow structure is about 80 degrees.

FIG. 5 shows an embodiment of the assembled pneumatic actuator joint inactuated position where the angle between the first and second hollowstructure is about 130 degrees.

FIG. 6A shows a schematic of an embodiment of the assembled pneumaticactuator joint in relaxed position where the first and second hollowstructures and are joint together with a metallic pin.

FIG. 6B shows a schematic of the assembled pneumatic actuator joint ofFIG. 6A in an actuated position.

FIG. 6C shows an image of the assembled pneumatic actuator joint with ametallic pin connecting the first and second hollow structures inrelaxed position.

FIG. 6D shows an image of the assembled pneumatic actuator joint with ametallic pin connecting the first and second hollow structures inactuated position.

FIG. 7A shows a schematic of an embodiment of the assembled pneumaticactuator joint in relaxed position where the first and second hollowstructures and are connected via door hinge joint.

FIG. 7B shows a schematic of the assembled pneumatic actuator jointshown in FIG. 7A in an actuated position.

FIG. 7C shows an image of the assembled pneumatic actuator joint with adoor hinge joint connecting the first and second hollow structures inrelaxed position.

FIG. 7D shows an image of the assembled pneumatic actuator joint with adoor hinge joint connecting the first and second hollow structures inactuated position.

FIG. 8 is a schematic of the insect robot limb including two assembledpneumatic actuator joints rotated with respect to each other by 180 degin accordance with this disclosure

FIG. 9 is an embodiment of the insect robot limb including two assembledpneumatic actuator joints on opposing sides of the insect robot limb,with both the actuators in relaxed position.

FIG. 10 shows the extension of the insect robot in FIG. 9 duringactuation.

FIGS. 11A, 11B, and 11C shows a crawling insect robot and the varioussteps involved in moving the crawling insect robot.

FIG. 12A shows another insect robot which couples two of the insectrobots limbs and at the body with the foot pointing in oppositedirections.

FIG. 12B shows an intermediate configurations for the insect robotduring motion from the right to the left direction.

FIG. 12C shows a subsequent configurations for the insect robot duringmotion from the right to the left direction.

FIG. 13A shows another embodiment of an insect robot which comprises offour robot limbs.

FIG. 13B shows that the condition of the insect robot that causes thefoot to be elevated from the ground to cause a motion in the directionof the insect robot limb

FIG. 13C shows the insect robot limb in a stretched out condition withthe foot extended and in contact with the ground.

FIG. 14 shows two embodiments of the insect demonstrating that theinsect robot can be scaled to larger sizes.

FIG. 15 shows an embodiment of the insect robot with four insect robotlimbs that is able to mimic the gait of a water strider by traversingacross the water surface while remaining afloat.

FIG. 16A shows a sketch of an embodiment of the insect robot with sixrobot limbs wherein four limbs have two pneumatic actuator joints andeach and two limbs have three pneumatic actuator joints.

FIG. 16B shows the side view of an embodiment of the insect robotaccording to FIG. 16A.

FIG. 16C shows the top view of an embodiment of the insect robotaccording to FIG. 16A.

FIG. 17A shows an embodiment of the insect robot with six insect robotlimbs that is able to mimic the gait of a water strider by traversingacross the water surface while remaining afloat.

FIG. 17B shows an embodiment of a modular pneumatic actuator joint withfabric reinforcement.

FIGS. 17C, 17D, 17E and 17F show the top view of the four successivestages of motion of an embodiment on an insect robot with size insectrobot limbs that is able to mimic the gait of a water strider bytraversing across the water surface while remaining afloat.

FIGS. 17G, 17H, 17I and 17J show the side view of the four successivestages of motion of an embodiment on an insect robot with size insectrobot limbs that is able to mimic the gait of a water strider bytraversing across the water surface while remaining afloat.

DETAILED DESCRIPTION

The present invention discloses modular pneumatic joints that areinsect-inspired and capable of a range of movements. These modularpneumatic actuator joints are prepared using a first and second hollowstructure that are connected at a point to form a joint such that theproximal ends of the first and second hollow structures that form thejoint can move towards and away from each other. At the joint, aninflatable bladder that inflates preferentially in one direction isdisposed and immobilized. On inflation of the bladder, the bladderextends in an outward direction away from the joint of the first and thesecond hollow structures. The outward motion causes the joint to ‘open’.A restraining membrane disposed over the bladder and attached to thefirst and the second hollow structures returns the join to its restingstate, thereby ‘closing’ the joint. The restraining membrane remains ina relaxed position when the bladder is deflated, holding the joint in aclosed position.

Modular Pneumatic Actuator Joint

FIG. 1A is a schematic of an embodiment of the assembled pneumaticactuator joint 100 when the actuator is in relaxed position. The jointfunctions as device connecting the first and second hollow structures101 and 102 and facilitates their movement around the joint.

An elastic bladder 103 is disposed and immobilized at the joint of firstand second hollow structures 101 and 102. The elastic bladder isselected to provide inflation in a direction away from the joint offirst and second hollow structures 101 and 102. In an embodiment thepreferential expansion of bladder 103 is achieved by variation in thethickness of the bladder walls with one side thinner than the remainingbladder, causing the bladder to preferentially inflate in the directionof the thinner-walled bladder section. In yet another embodiment, theinflation of bladder 103 causes preferential expansion in one directionsby providing restraining walls in first and second hollow structures 101and 102. Upon inflation, the bladders inflates and is arrested by thewalls provide in first and second hollow structures 101 and 102 and theinner body of the first and second hollow structures 101 and 102, withonly one direction available for expansion, which is away from the jointof first and second hollow structures 101 and 102. Connective tubing 104transports gas to and from elastic bladder 103 causing it to inflate ordeflate.

A restraining membrane 105, made of an elastic material, is attached atone end to first hollow structure 101 and at the other end to secondhollow structure 102. Further, restraining membrane 105 is disposed sothat it remains in contact with the bladder material when the modularpneumatic actuator joint is in rest position. In an embodimentrestraining membrane 105 is attached to first and second hollowstructures 101 and 102 by an adhesive or secured by tying with a string,rope or a similar fastening device. In yet another embodiment,restraining membrane 105 is firmly secured to first and second hollowstructures by tying it with a rope or a string. In yet anotherembodiment, first and second hollow structures 101 and 102 have hooks orsimilar attachment devices and restraining membrane 105, is disposed onthe attachment devices on first and second hollow structures 101 and 102by means of threading the elastic through complementary holes on bothends of restraining membrane 105, one corresponding to each of first andsecond hollow structures 101 and 102.

The joint of first and second hollow structures 101 and 102 can beachieved by cutting a notch into a straight hollow structure tointroduce tapered edges that meet in a relaxed state and separate in anactuated state. In some embodiments first and second hollow structures101 and 102 are joined together by a web of material integral to the twohollow ends. In yet another embodiment, first and second hollowstructures 101 and 102 are joined together by a hinge or a metallic pinpassing through holes provided at the point where the first and secondhollow structures 101 and 102 meet. One skilled in the art would be ableto device other methods not disclosed here to join first and secondhollow structures 101 and 102 that allows them to open and close at thejoint connecting them.

FIG. 1B is a schematic that shows that varying the angle of cut 106 and107 of first and second hollow structures, 101 and 102 with respect tothe central axis 108 and 109 of first and second hollow structuresgoverns the angle that is achieved in the relaxed position. By makingthe angle of cut of first and second hollow structures, 106 and 107 withrespect to the central axis of first and second hollow structuressmaller, a smaller angle at relaxed position 110 for the actuator can beattained.

In an embodiment, angle of cut to central axis of the hollow structures106 and 107, is the same. In yet another embodiment, angle of cut to thecentral axis of the hollow structures 106 and 107, is not the same.

Advantageously, the angle of cut to the central axis of the hollowstructures 106 and 107 can be used to specifically control the range ofmotion achieved by the modular pneumatic actuator joint 100. In someembodiments, the angle of cut, relative to the central axis of thehollow structures 106 or 107, can be individually selected to be between5 degrees and 85 degrees.

FIG. 2 is a schematic illustration of an embodiment of an assembledpneumatic actuator joint 200 while in the actuated position. An elasticbladder 203, that is disposed and immobilized at the joint of a firstand second hollow structures 201 and 202, is inflated by pressurizingbladder 203 through transport of air into the bladder through theconnective tubing 204 such that bladder 203 inflates in a direction awayfrom the joint of first and second hollow structures 201 and 202(indicated by arrows 220). The inflation of elastomeric bladder 203through transport of gas into the bladder, results in the application ofa positive pressure on the restraining membrane 205 causing it tostretch away from the joint of first and the second hollow structures201 and 202. At the same time the inflated bladder 203 also applies aforce on both first and second hollow structures 201 and 202 causing thedistal ends of the modular pneumatic actuator to move away from eachother by around the joint.

Upon removal of the applied pressure, the gas that inflates elastomericbladder 203 is transported out back through the connective tubing 204relieving the positive pressure on restraining membrane 205. This causesrestraining membrane 205 to contract causing the distal ends of firstand second hollow structures 201 and 202 to move towards each otheraround the joint. This results in the modular pneumatic actuator joint200 to return to its relaxed position as shown in FIG. 1A.

In some embodiments the actuated position of the modular pneumaticactuator joint forms an angle ranging from about 20 degrees to about 180degrees between first and second hollow structures 201 and 202.

FIG. 3 shows the various components used for making the modularpneumatic actuator joint according to one embodiment. A hollow structure310 is used to produce the first and second hollow structures 301 and302. In some embodiments, the hollow structure 310 is notched to leavethe resulting hollow structures 301 and 302 connected to each other at apoint, about which the distal end of the hollow structures 301 and 302can move away or towards each other. In some embodiments the materialused for producing this are selected from a group consisting ofaluminum, copper, brass, polypropylene, poly(vinyl chloride),polycarbonate, poly(tetrafluoroethylene), polyisobutylene, polystyrene,polyacrylonitrile, poly(methyl acrylate), poly(methyl methacrylate),polybutadiene, polychloroprene, poly(cis-1,4-isoprene), andpoly(trans-1,4-isoprene). In an embodiment, the first and second hollowstructures 301 and 302, respectively of the modular pneumatic actuatorjoint can be made using polypropylene straws. 313 is a tubularelastomeric material that is used to form an inflatable bladder 303which inflates preferentially in one direction. 304 is connective tubingthat is used to transport the gas to and away from inflatable bladder303. The inflatable bladder is made of a material that is elastomericand can be selected from a group consisting of polyisoprene,polybutadiene, polyurethane, polychloroprene, butyl rubber, halogenatedbutyl rubber, styrene-butadiene rubber, nitrile rubber, hydrogenatednitrile rubber, ethylene propylene rubber, ethylene propylene dienerubber, epichlorohydrin rubber, polyacrylic rubber, silicone rubber,fluorosilicone rubber, fluoroelastomers, perfluoroelastomers, polyetherblock amides, chlorosulfonated polyethylene, ethylene-vinyl acetate, andpolysulfide rubber. In an embodiment, the inflatable bladder is made byheat sealing the elastomeric material at the edges with an openingprovided by the connective tubing 304 to facilitate transport of gas tobe used for pressurizing the bladder 303. 315 is another elastomericmaterial that is used to form a restraining membrane 305 that isdisposed to cover inflatable bladder 303 and attached to first andsecond hollow structures 301 and 302. Restraining membrane 305 is madeof a material that is elastomeric and can be selected from a groupconsisting of polyisoprene, polybutadiene, polyurethane,polychloroprene, butyl rubber, halogenated butyl rubber,styrene-butadiene rubber, nitrile rubber, hydrogenated nitrile rubber,ethylene propylene rubber, ethylene prorpylene diene rubber,epichlorohydrin rubber, polyacrylic rubber, silicone rubber,fluorosilicone rubber, fluoroelastomers, perfluoroelastomers, polyetherblock amides, chlorosulfonated polyethylene, ethylene-vinyl acetate, andpolysulfide rubber. In an embodiment, restraining membrane 305 is madeof strips cut from an air balloon.

FIG. 4 is a photograph of a pneumatic actuator joint prepared using thematerials and components shown in FIG. 3. FIG. 4 shows an embodiment ofan assembled pneumatic actuator joint 400 in relaxed position where theangle between the first and second hollow structure 401 and 402 is about80 degrees. In the relaxed position, the elastomeric bladder 403 is in adeflated state and the restraining membrane 405 is not stretched.

FIG. 5 shows an embodiment of the assembled pneumatic actuator joint 500in actuated position where the angle between the first and second hollowstructure 501 and 502, is about 130 degrees. Upon actuation, theelastomeric bladder 503 is inflated and applies pressure on therestraining membrane 505 causing it to be stretched away from the jointof first and second hollow structures 501 and 502. At the same timeinflated bladder 503 also applies a force on both first and secondhollow structures 501 and 502 causing the distal ends of the modularpneumatic actuator to move away from each other around the joint.

The movable joint can be implemented in the device in a number of ways.In one or more embodiments, the joint can be a thinned strip of the samematerial used for the first and second hollow elements; the joint can beintegral with the first and second hollow elements. In otherembodiments, when the material of the thinned strip is made of adifferent material other than the first and second hollow elements, eachof the two ends of the thinned strips are glued to the end of the firstand second hollow element where they are connected. In otherembodiments, the movable joint can be a pin. A pin is a thin strip ofmetal that is used to form a joint connecting the first and secondhollow elements. In some embodiments, each end of the pin is passedthrough a hole located at the end of the first and second hollow elementwhere the two hollow elements are connected and held in place throughcommonly used methods that form a head at the end of the pin which has alarger diameter than the hole in the first and second hollow elementsand the diameter of the body of the pin itself. Some commonly usedmethods that form a head to secure a pin are, placement of bolt at theend of the pin, flattening the material at end of the pin to form ahead, splitting the end of the pin to form prongs and bending the splitprongs radially away from each other. An individual with ordinary skillin the art can envisage other methods for securing the pin to connectthe first and second hollow element. In other embodiments, the movablejoint can be a ring that passes through a hole located at the end of thefirst and second hollow element where the two hollow elements areconnected. In other embodiments, the movable joint can be a hinge,having for example a configuration similar to a door hinge. Each of thetwo ends of the hinge are glued to or screwed on to the end of the firstand second hollow element where they are connected.

FIG. 6A shows a schematic of an embodiment of the assembled pneumaticactuator joint 600 in relaxed position where the first and second hollowstructures 601 and 602 are joint together with a metallic pin. FIG. 6Bshows a schematic of the assembled pneumatic actuator joint 600 in anactuated position. FIG. 6C shows an image of the assembled pneumaticactuator joint 600 in relaxed position. FIG. 6D shows an image of theassembled pneumatic actuator joint 600 in actuated position.

FIG. 7A shows a schematic of an embodiment of the assembled pneumaticactuator joint 700 in relaxed position where the first and second hollowstructures 701 and 702 are connected via door hinge joint 703. FIG. 7Bshows a schematic of the assembled pneumatic actuator joint 700 in anactuated position. FIG. 7C shows an image of the assembled pneumaticactuator joint 700 in relaxed position. FIG. 7D shows an image of theassembled pneumatic actuator joint 700 in actuated position.

In some embodiments, the joint of the assembled pneumatic actuatorcomprises of a housing which contains the inflatable bladder. In someembodiments, the housing is 3D printed.

Insect Robot Limb

In another aspect, using modular pneumatic actuator joints described inthe preceding section it is possible to fabricate a two stage actuator,modeled after insect limbs; herein after referred to as “insect robotlimbs”. Each insect robot limb can include at least one modularpneumatic actuator joint. In one or more embodiments, each insect robotlimb includes more than two modular pneumatic actuator joints. In one ormore embodiments, the joints are actuated together. In one or moreembodiments, the joints have the ability to be actuated independently,by providing a separate gas actuation source for each joint.

FIG. 8 is a schematic of the insect robot limb 800 including twoassembled pneumatic actuator joints in accordance with this disclosure.In this embodiment of the insect robot limb, the modular pneumaticactuator joints are attached to each other directly, that is, they areformed from a single hollow tube that has been modified to contain twojoints. With reference to FIG. 8, a single hollow structure 801 containstwo sets of tapered edges, 8′, 801″ and 802′, 802″, which form joints810 and 820, respectively. Each joint 810 and 820 is equipped with abladder 813 and 823, and a restraining structure 815 and 825,respectively. Depending on the location of the joints (discussed indetail below), the restraining structures can integral or separateelements. Each joint 810 and 820 also is in fluidic communication with apressurization source. Individual sources 814 and 824 can be used toprovide independent actuation. Alternatively, a single source can beused to serially communicate with a plurality of bladders. In one moreembodiments, actuation occurs as previously described.

The spacing and location of the joints can be selected to obtain adesired type and range of motion. For example, when it is desired forthe robot to exhibit extension motion, the joints can be located on theopposite side of the insect robot limb. FIGS. 9 and 10 illustrate thisrange of motion. FIG. 9 is an embodiment of the insect robot limb 700including two assembled pneumatic actuator joints 910 and 920 onopposing sides of the insect robot limb, with both the actuators inrelaxed position. FIG. 10 shows the extension of the insect robot 700after actuation. Note the visible expanded bladder at each of thejoints.

In yet another embodiment of the pneumatic insect robot limb 800, themodular pneumatic joints of the first and second modular pneumaticactuator 810 and 820, are facing the same side. Such an arrangement canbe selected when a closing or ‘grasping’ motion is desired. In yetanother embodiment of the pneumatic insect robot, the modular pneumaticjoints of the first and second modular pneumatic actuators 810 and 820,are not facing the same side.

In an embodiment of the insect robot limb 800, the modular pneumaticactuator joints 810 and 820, can be attached to each to each other usinganother hollow structure of predetermined length. In yet anotherembodiment of the insect robot limb 800, the connective tubing 814 and824, transporting gas to and from the bladder is substantially containedinside the hollow structures of the limb. In yet another embodiment ofthe insect robot limb, the connective tubing substantially travels alongthe hollow structures of the insect robot limbs.

Insect Robots and their Motion

In another aspect of the invention, insect robots providing a range ofmotion can be produced by using one or more of the above describedinsect robot limbs. In some embodiments there is only one modularpneumatic actuator joint in an insect robot limb. In yet anotherembodiment, there are two modular pneumatic actuator joints in an insectrobot limb. In yet another embodiment there are more than one modularpneumatic actuator joints in an insect robot limb. As the number ofinsect robot limbs increase in the insect robot, the number ofdirections and complexity of sequence available to move the insect robotalso increases. In some embodiments, when there are more than one insectrobot limbs used to produce the insect robot, the number of modularpneumatic actuator joints in the various insect robot limbs are same. Inyet another embodiment, when there are more than one insect robot limbsused to produce the insect robot, the number of modular pneumaticactuator joints in the various insect robot limbs are different. In yetother embodiments, the insect robot can have a combination of actuatableand rigid limbs. See, e.g., FIG. 17.

In some embodiments, a friction enhancing material is disposed on theend of the insect robot limb or limbs, that may come in contact with theground during motion to enhance the movement of the insect robot. Thefriction enhancing material can be made of material such as, but notlimited to, an abrasive or a textured surface made of silicone orrubber.

FIGS. 11A, 11B, and 11C show an embodiment of a crawling insect robot900 and the various steps involved in moving the crawling insect robot.FIG. 11A shows a crawling insect robot 1100 with one insect robot limb1101 having two modular pneumatic actuator joints 1110 and 1120 and afoot 1130 and a body 1140. The foot 930 provides a means to provideinitial contact with the surface ahead in the direction of movement oncethe joints are actuated. Upon regaining contact with the ground at apoint ahead of the initial location the limb anchors to the new locationand drags the remaining body 1140 forward using the steps describedbelow.

The insect robot 1100 is shown with both the modular pneumatic actuatorjoints 1110 and 1120 in their relaxed position and the foot of theinsect robot 1130 pointing in the direction of the desired motion. Insome embodiments, foot 1130 of the insect robot limb has a frictionenhancing material disposed on it. In another embodiment, body 1140 ofthe insect robot can be equipped with a floatation device to enable itto remain afloat on a liquid medium. In yet another embodiment, foot1130 can be modified into paddling device to facilitate forward movementthrough the liquid medium.

Movement in the direction indicated by the arrow in FIG. 11A ispossible. To move insect robot 1100 in a direction from left to right,independently controlled modular pneumatic actuator joint 1120 is firstactuated and brought into an actuated position. FIG. 11B shows theintermediate step that is attained when the modular pneumatic actuator1120, is in an actuated position and the foot of the insect 1130 is inair. This step is followed by actuation of modular pneumatic actuatorjoint 1110 to bring it to an actuated position. Once, modular pneumaticactuator joint 1110 is completely actuated the foot of the insect robot1130 is again in contact with the ground and both modular pneumaticactuator joints 1110 and 1120 are in an actuated position. FIG. 11Cshows the configuration when both the modular actuator joints 1110 and1120, are in an actuated position and the insect foot 1130 is in contactwith the ground. Subsequently, both the modular pneumatic actuatorjoints are brought back into their relaxed positions by deflating themin either a sequence or simultaneously. By first deflating the modularactuator joint 1120 then deflating 1110, forward movement is created.The body of the robot 1140 moves in the direction of the foot 1130caused the entire crawling insect robot to be effectively displaced inthe direction of the foot. Further, this restores the crawling insectrobot to its condition shown in FIG. 11A and the cycle described in FIG.11A through FIG. 11C can be repeated successively to attain displacementover large lengths.

FIG. 12A shows another embodiment of an insect robot 1200 in which twoof the insect robots 1100 i and 1100 ii are attached to each other attheir respective bodies 1140 i and 1140 ii by a connecting device 1201,in such a way that their respective feet 1130 i and 1130 ii are pointingin opposite directions. This facilitates movement in two oppositedirections. Actuating pneumatic actor 1120 i on the insect robot 1100 iand 1110 ii on insect robot 1100 ii result in the foot 1130 i of theinsect robot 1100 i to be raised from the ground while the foot 1130 iiof the insect robot 1100 ii still remains in contact with the ground.This sequence of actuation causes the insect robot 1200 to be move inthe direction of the foot 930 i due to the actuation of the pneumaticactuator 1110 ii. FIG. 12B shows this intermediate position. As a nextstep the pneumatic actuators 1110 i and 1120 ii are actuated resultingin all the four pneumatic actuators of the insect robot to be inactuated state. Since the foot 1130 ii is still in contact with theground this causes the insect robot to further move forward in thedirection of the foot 1130 i and the foot 1130 i returns to come incontact with the ground. In the next step the actuators 1120 i and 1110ii are depressurized while 1110 i and 1120 ii are held in actuatedposition. This results in the foot 1130 ii to be raised up off theground and the body section 1140 i and 1140 ii of the insect robot toslide further in the direction of the foot 1130 i This is shown in FIG.12C. Finally, the actuators 1110 i and 1120 ii are depressurized and theinsect robot is returned to its starting position. Additional cycles maybe repeated to advance the insect robot further in the same direction.Motion in the opposite direction i.e., in the direction of insect robot900 ii, can be attained by inverting the sequence of actuation anddepressurization of the actuators.

FIG. 13A shows another embodiment of an insect robot 1300 whichcomprises of four insect robot limbs 1301, 1302, 1303 and 1304, eachhaving a foot in contact with the ground. Thus, 1301 is in contact withthe ground on foot 1331, 1302 is in contact with the ground on foot1332, 1303 is in contact with the ground on foot 1333, and 1304 is incontact with the ground on foot 1334. In some embodiments the foot has afriction enhancing material disposed on it. Further, each limb comprisesof two modular pneumatic actuator joints. Thus, 1101 comprises, twomodular pneumatic actuator joints 1311 and 1321, 1302 comprises, twomodular pneumatic actuator joints 1312 and 1322, 1303 comprises, twomodular pneumatic actuator joints 1313 and 1323, and 1304 comprises, twomodular pneumatic actuator joints 1314 and 1324. The four insect limbs1301, 1302, 1303 and 1304 are further held together beyond the modularpneumatic actuator joints 1311, 1312, 1313 and 1314 with a rigid bracket1317.

The insect robot 1300 provides a range of movement in four directionsdepending on the predetermined sequence of actuating of the modularpneumatic actuators. In one sequence to move the insect robot 1300 froma resting position, where all the modular pneumatic actuator joints arein a resting position, in the direction of insect robot limb 1304 themodular pneumatic actuator joints 1312, 1322, 1314 and 1324 are actuatedin a predetermined sequence. This sequence is carried out by firstactuating the modular pneumatic actuator joint 1324 which is locatedcloser to foot 1334, and the pneumatic actuator joint 1312, on theinsect robot limb 302, simultaneously, while keeping the other modularpneumatic actuators in resting position. FIG. 13B shows the resultingconfiguration where the insect foot 1334 is elevated from the ground.Subsequently, modular pneumatic actuator joints 1314 and 1322 arepressurized. This causes the insect robot limb 1304 to be stretched outand the foot 1334 to return in contact with the ground. After this step,modular pneumatic actuator joints 1312 and 1322 are sequentiallydepressurized to a relaxed position. FIG. 13C shows the resultingposition. Other actuation sequences can be used to accomplish differentranges and types of motion.

FIG. 14 shows two embodiments of the insect demonstrating that theinsect robot can be scaled to larger sizes. 1401 is a four legged insectrobot, similar to one discussed in FIG. 13 with a foot span of 14 cm.1402 is a scaled up version of the same robot with a foot spacing of 25cm. This is attained either by elongating the first and second hollowstructures that make up the modular pneumatic actuator joint andconnecting them directly, or by using larger sizes of intermediateconnecting hollow structures to connect the pneumatic actuator joints.

In some embodiments, the weight of the final insect robot is controlledthrough the choice of the materials selected in its fabrication. Forexample, the insect robots can be made from lightweight materials sothat it can remain afloat on the surface of liquid such as water byrelying on the surface tension and buoyancy from the liquid. In one ormore embodiments, the feet of the robot can be modified to assist inflotation or paddling in the liquid. FIG. 15 shows an embodiment of aninsect robot with four insect robot limbs that is able to mimic the gaitof a water strider and remain afloat the water surface and traverseacross it.

FIG. 16A shows an embodiment of an insect robot 1400 with six pneumaticrobot limbs, of which four limbs 1601, 1602, 1603, and 1604, have twopneumatic actuators where as two limbs, 1605 and 1606, have threepneumatic actuators. FIG. 16B shows the side view of the insect robot1600 and FIG. 16C shows the top view.

FIG. 17A shows an embodiment of an insect robot with six insect robotlimbs 1701, 1702, 1703, 1704, 1705 and 1706 that is able to mimic thegait of a water strider and remain afloat the water surface and traverseit. In an embodiment, only the two middle insect robot limbs 1703 and1704 have pneumatic actuator joints. Pneumatic actuator joints 1713,1723 are located on the insect robot limb 1703 and the pneumaticactuator joints 1714 and 1724 are located on the insect robot limb 1704present in them that provide a bending motion. In some embodiments thepneumatic actuator joints are reinforced with a fabric to provideadditional support. In yet another embodiment, the fabric of thematerial used is stretchable such as spandex. FIG. 17B which shows apneumatic actuator joint reinforced with spandex fabric.

FIGS. 17C through 17F and 17G through 17J show the top view and sideview, respectively of the four steps in chronological order required formoving the water strider shown in FIG. 17A forward. FIGS. 17C and 17Gshow the initial relaxed position. In FIGS. 17D and 17H the pneumaticactuator joints 1713 and 1714 are actuated to initiate a backstrokecausing the insect robot limbs 1703 and 1704 to move backward.Subsequently, the pneumatic actuator joints 1723 and 1724 are actuatedto cause the feet 1733 and 1734 to be raised from the surface of theliquid. In this situation the insect robot 1700 is afloat the surface ofthe liquid on feet 1731, 1732, 1735 and 1736. In the next step thepneumatic actuators 1713, 1714 and 1723 and 1724 are depressurized toreturn to relaxed state to complete a cycle for advancing the insectrobot 1700 in the direction from right to left according to the sideview images FIGS. 17G through 17J.

The insect robot 1700 as shown in FIG. 17A can be rotated by keeping allthe insect robot limbs stationary while moving only one limb. Forinstance, keeping limbs 1701, 1702, 1703, 1705 and 1706 in a stationaryposition and actuating the pneumatic actuator joints 1714 and 1724 in apredetermined sequence can cause the insect robot 1700 to turn in eitherdirections.

In some embodiments the gas used for inflating the bladder is compressedair. In yet another embodiment, the gas used for inflating the bladdersof the modular pneumatic actuator joints is supplied by a cylinder orportable air compressor that is housed on the insect robot

In some embodiments, the pressure source coupled to the modularpneumatic actuator joint can be controlled using software running on acomputational device. The software needed for implementing the controlprocess includes a high level procedural or an object-orientatedlanguage such as MATLAB, C, C++, Java or Perl. The software may also beimplemented in assembly language if desired. In certain embodiments, thesoftware is stored on a storage medium or device such as read onlymemory (ROM), programmable-read-only memory (PROM), electricallyerasable programmable-read-only memory (EEPROM), flash memory, or amagnetic disk that is readable by a general or specialpurpose-processing unit to perform the processes described in thisdocument. The processors can include any microprocessor (single ormultiple core), system on chip (SoC), microcontroller, digital signalprocessor (DSP), graphics processing unit (GPU), or any other integratedcircuit capable of processing instructions such as an x86microprocessor.

In some embodiments, the insect robot is fabricated using low costmaterials that are readily available significantly reducing the cost ofthe device. In a one or more embodiments, the hollow structures of therobot could be fabricated with PVC pipes, the restraining membrane couldbe made using rubber from a tire tube, rubber pipes could be used forthe connective tubing and the inflatable bladder could also be made ofrubber from a tire tube which is heat pressed and sealed to facilitateinflation in a preferential direction.

The insect based robot can be used for a variety of applications.Specifically, since the robot can be fabricated in a cost effective way,it can be deployed for functioning where retrieval after completion ofthe operation is not feasible. For example, in areas of hazardous wasteand hostile environmental conditions not suitable for access by humanbeings.

Although the present disclosure has been described and illustrated inthe foregoing example embodiments, it is understood that the presentdisclosure has been made only by way of example, and that numerouschanges in the details of the implementation of the disclosure may bemade without departing from the spirit and scope of the disclosure,which are limited only be the claims which follow. Other embodiments arewith the following claims.

1. A modular pneumatic robotic actuator, comprising: a first elongatedrigid structure and a second elongated rigid structure connected to eachother at a moveable joint, wherein the movable joint is disposed at afirst angle when the moveable joint is unactuated and a second anglewhen the moveable joint is actuated; and a restraining membranecomprised of an elastomeric material connecting the first and secondrigid structures, wherein the restraining membrane is in a relaxedposition in the unactuated state and an extended position in theactuated state, and wherein the restraining membrane in the extendedposition provides a restoring force to the actuator to return themovable joint to the first angle.
 2. The actuator according to claim 1,wherein the restraining membrane is attached to the first and secondrigid structures by an adhesive.
 3. The actuator according to claim 1,wherein the restraining membrane is attached to the first and secondrigid structures by a rope or string.
 4. The actuator according to claim1, wherein the first and second rigid structures have hooks and therestraining membrane is attached to the hooks of the first and secondrigid structures.
 5. The actuator according to claim 1, wherein thefirst and second rigid structure is made of a material selected from agroup consisting of aluminum, copper, brass, polypropylene, poly(vinylchloride), polycarbonate, poly(tetrafluoroethylene), polyisobutylene,polystyrene, polyacrylonitrile, poly(methyl acrylate), poly(methylmethacrylate), polybutadiene, polychloroprene, poly(cis-1,4-isopren),and poly(trans-1,4-isoprene).
 6. The actuator according to claim 1,wherein the restraining membrane is made of an elastomeric materialselected from the group consisting of polyisoprene, polybutadiene,polyurethane, polychloroprene, butyl rubber, halogenated butyl rubber,styrene-butadiene rubber, nitrile rubber, hydrogenated nitrile rubber,ethylene propylene rubber, ethylene propylene diene rubber,epichlorohydrin rubber, polyacrylic rubber, silicone rubber,fluorosilicone rubber, fluoroelastomers, perfluoroelastomers, polyetherblock amides, chlorosulfonated polyethylene, ethylene-vinyl acetate, andpolysulfide rubber.
 7. The actuator according to claim 1, wherein thejoint comprises a web of material that is integral to the first andsecond rigid structures.
 8. The actuator according to claim 1, whereinthe joint is a thinned strip of the same material used for the first andsecond rigid structures.
 9. The actuator according to claim 1, whereinthe joint is a thinned strip of a material different than that used forthe first and second rigid structures.
 10. The actuator according toclaim 1, wherein the joint is a pin provided at the point where thefirst and second rigid structures meet.
 11. The actuator according toclaim 1, wherein the joint is a ring that passes through a hole locatedat the end of the first and second rigid structures where the two rigidstructures are connected.
 12. The actuator according to claim 1, whereinthe joint is a hinge.
 13. The actuator according to claim 1, wherein thejoint comprises a notch cut into the first and second rigid structuresto introduce tapered edges that meet in the unactuated state and thatseparate in the actuated state.
 14. The actuator of claim 1 wherein aninflatable bladder is disposed between the joint and the restrainingmembrane.
 15. The actuator according to claim 14, wherein the inflatablebladder, the restraining membrane, and a substantial part of the firstand second rigid structures are covered by a fabric material.
 16. Amethod of actuating a modular pneumatic robot actuator according toclaim 14 comprising: pressurizing the inflatable bladder with a gas toinflate the bladder wherein the inflatable bladder exerts a force on therestraining membrane causing the moveable joint to open.
 17. The methodof claim 16 further comprising: depressurizing the inflatable bladder todeflate the bladder wherein the force exerted on the restrainingmembrane is thereby removed and the restraining membrane causes themoveable joint to close.